Ecology Flashcards
(21 cards)
Modified populations
Populations humans interfere with - through hunting, harvesting, translocation
Density of population
Not static - births, deaths, migration
Demography
Key characteristics of a population
Quantifying pattens - who stays/goes/lives/dies
Survivorship curves
How many individuals alive at each age
Type one - humans (low offspring high survival)
Type 2 - squirrels (decrease steadily)
Type 3 - tree (lots of young, reduce quick)
Stepped curves - death rate higher at certain life stages
K selection life history
Population living near limits imposed by resources ; at or near carrying capacity
Eg mature trees in old growth forest
R selection life history
Populations have unlimited resources
Eg weeds in disturbed gardens
Density independent factors
Forces that affect size of population regardless of birth/death rate eg cyclone
Density dependant
Births / Deaths dependant on population growth. Usually halts growth
Eg disease
Dispersion
Pattern of spacing among individuals within the boundaries of a population
Clumped, - water, food
Uniform - territories, burrows
Random - resting animals, weed dispersal
Dispersal
Process involving the movement of individuals away from the population they were born in to another to settle and reproduce
Active dispersal
Fly, swim, walk, run
Passive dispersal
Float, raft, transported
Dispersal barriers
Barriers that limit physical movement
Anthropogenic, physical, behavioural
Range expansion
Expansion of an area a species is found in - natural or human influenced
Eg cane toads
Metapopulations
A number of local populations that
are linked - occupy discrete patches of suitable habitat surrounded by unsuitable habitat
- spatially discrete (migration limited)
- extinction risk
- not static
Possible meta population structures
Classical (uniform/natural)
Patchy (random)
Mainland-island
Non-equilibrium (highly isolated, low interaction between pop)
Attributes of habitat patches
Size appropriate
Quality
Isolation
Within dispersal distance
Ability for organisms to establish
Ways of tracking movement
Tagging (bands, gps or satellite)
Genotyping (sex, relatedness, tissue, scat, hair, eDNA)
Photo id (natural markings, drones, ai, videos)
Rates of movement (individual/generational)
Physical plant defences
- thorns
- trichromes (hairy insect deterrents)
- waxy surface
- leaf structure (thick cell walls)
Aquatic plant defences
Thinner structures to maximise light and carbon
More likely to have chemical defences
Herbivore offense
Toxins for own defences
Food choice
Eat tissues with high nutritional value and low toxins
Morphological evolution around digestion
